Comparison of numerical models for prediction of pressure-swirl atomizer internal flow

review

en

Numerical prediction of discharge parameters allows to design a pressure-swirl atomizer in fast and cheap manner, yet it must provide reliable results for a wide range of geometries and operating regimes. Many authors used different numerical setups for similar cases and often concluded opposite suggestions on numerical setup. This paper compares 3D (three-dimensional) periodic numerical models used for estimation of the internal flow characteristics of a pressure-swirl atomizer. The computed results are compared with experimental data in terms of spray cone angle, discharge coefficient (CD), internal air-core dimensions, and velocity profiles. The internal air-core was visualized by high-speed camera with backlit illumination. Tested conditions covered wide range of the Reynolds numbers within the inlet ports, Re = 1000, 2000, 4000. The flow was treated as both steady and transient flow. The numerical solver used laminar and several turbulence models, represented by k-ε and k-ω models, Reynolds Stress model (RSM) and Large Eddy Simulation (LES). The laminar solver was capable to closely predict the CD, air-core dimensions and velocity profiles compared with the experimental results. The LES performed similarly to the laminar solver for low Re and was slightly superior for Re = 4000. The two-equation models were sensitive to proper solving of the near wall flow and were not accurate for low Re. Surprisingly, the RSM produced worst results.

Numerical prediction of discharge parameters allows to design a pressure-swirl atomizer in fast and cheap manner, yet it must provide reliable results for a wide range of geometries and operating regimes. Many authors used different numerical setups for similar cases and often concluded opposite suggestions on numerical setup. This paper compares 3D (three-dimensional) periodic numerical models used for estimation of the internal flow characteristics of a pressure-swirl atomizer. The computed results are compared with experimental data in terms of spray cone angle, discharge coefficient (CD), internal air-core dimensions, and velocity profiles. The internal air-core was visualized by high-speed camera with backlit illumination. Tested conditions covered wide range of the Reynolds numbers within the inlet ports, Re = 1000, 2000, 4000. The flow was treated as both steady and transient flow. The numerical solver used laminar and several turbulence models, represented by k-ε and k-ω models, Reynolds Stress model (RSM) and Large Eddy Simulation (LES). The laminar solver was capable to closely predict the CD, air-core dimensions and velocity profiles compared with the experimental results. The LES performed similarly to the laminar solver for low Re and was slightly superior for Re = 4000. The two-equation models were sensitive to proper solving of the near wall flow and were not accurate for low Re. Surprisingly, the RSM produced worst results.

Internal flow, CFD, Laminar, air-core

02.09.2021

ILASS - Europe, Institute for Liquid Atomization and Spray Systems

Edinburgh

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